1. Field of the Invention
The invention relates to a copy holder, more particularly to a document holder which is to be mounted on a display terminal, such as a cathode ray tube display, such that an adjustment of the viewing angle of the display terminal will result in the document holder remaining in the same relative position with respect to the display terminal screen.
2. Description of the Prior Art
The construction of document holders used to support a document which contains information which is to be entered by an operator through a data entry keyboard attached to a display terminal such as used in factories, offices or the like, is based on the recognition that the best possible efficiency of a display terminal operator is only achieved if the operator can suitable assume a comfortable and an anatomically correct position with respect to the document which he is entering or referencing while stationed at the display terminal. In a data processing environment this means placing the display terminal viewing area, such as the screen of a CRT display terminal, at a comfortable height, distance and angle from the terminal operator's eyes and also placing the document which is to be referenced or entered in an equally comfortable position. Also, such a correct viewing position contributes considerably to the operator remaining in health--reducing eye strain, posture fatigue, etc.
There exists in the marketplace many document holders, or copy holders, which range from the simple and inexpensive to the complex and costly. An example of a simple document holder is that constructed of a one piece of sheet metal bent into a shape similar to a leaning L when viewed from the side. In this document holder, the vertical surface is slightly reclining away from the user and is used to support the document being referenced. The bottom of the L is the base of the document holder and is used to support the document holder in a more or less vertical position. This document holder works fairly well for a secretary while seated at a typewriter because they can position it to the left or right side of the typewriter on the same surface on which the typewriter is supported. When used in this fashion, this holder provides for holding the document in approximately the same viewing position as the document being produced in the typewriter.
There are many variations for this easel type of document holder. Some permit the adjustment of the easel surface so that it can be reclined, or tilted, toward or away from the operator. Other features have been added such as magnetic paper holders to retain the document to the easel surface and various line guides which may be moved in the vertical direction so that operators can keep track of their position on the document they are entering or referencing. An example of a simple easel document holder is shown in FIG. 1 in which element 11 is a sheet metal easel and element 12 is a magnetic page holder.
With the introduction of computer terminals which have a height greater than most typewriters, the need to place the document holder at a greater height from the table than is possible by the simple document holders has been recognized. FIG. 2 shows such a prior art document holder in which the document easel 23 is supported by a supporting rod 22 which is in turn attached to a base 21 which rests on the table next to the display terminal. The document holder of FIG. 2 has the advantage that it may position the referenced document at approximately the same height as the terminal's display area, that is the print head of the display terminal, such that the operator of the terminal may reference quickly between the terminal output and the document on the document holder.
Other document holders exist which have a base that rests on the table which supports the terminal. Other document holders attach to an edge of the table and which support the document easel by one or two flexible shafts, such as found on gooseneck lamps, which can be bent to change the position of the document easel thereby allowing the document to be placed in a comfortable viewing position. Still others exist which have multi-member arms which are spring counterbalanced such that the height and position of the document easel can be adjusted over a wide range.
With the introduction of cathode ray tubes for use as a display device on terminals, various terminal manufacturers have recognized the need for being able to adjust the tilt and swivel of the display screen for viewing convenience. Such adjustment may be necessary to adjust the difference positions assumed by the operator during the course of operation, to adjust the viewing angle to minimize the reflection of ambient light off the display screen, or due to the face that the same display terminal is used by a variety of operators during the course of a single day's business.
Therefore, what is needed is an inexpensive document holder which can be easily adjusted for viewing angle as the viewing angle of the display terminal is adjusted.